Examine source code of Insert Time

{
  "manifest_version": 2,
  "name": "Insert Time",
  "version": "1.0",
  "description": "inserts the current time into an input field in the browser",
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "inserttime.js"
      ]
    }
  ]
}